The present invention relates to a cooling apparatus and, more particularly, to a cooling apparatus for cooling a computer or similar electronic equipment by circulating a liquid coolant to a device of interest which is incorporated in the housing and generates heat.
It is a common practice with the above-described type of cooling apparatus to pump a secondary cooling liquid from a tank to a device which should be cooled and to deliver the liquid having absorbed heat to a heat exchanger. In such a case, a primary cooling liquid such as water is fed from a primary cooling liquid source to the heat exchanger via a three-way valve to exchange heat with the secondary cooling liquid. The opening degree of the three-way valve and, therefore, the amount of supply of the primary cooling liquid to the heat exchanger is controlled by a modutrol motor which is driven by a control signal fed from a controller. The problem with such a conventional cooling system is that when the modutrol motor fails to operate accurately due to some error, the temperature of the secondary cooling liquid is apt to fall excessively and, in the worst case, causes dew condensation to occur in the equipment. Then, not only the operation of the cooling apparatus but also the operation of the equipment itself has to be interrupted.